I have a Xamarin Forms application with a TabbedPage that contains different Children pages. I want to be able to know which child (tab) is active from my viewmodel. So I can
The ServiceListPage.xaml looks like this:
<?xml version="1.0" encoding="utf-8" ?>
<pages:BaseTabbedPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:pages="clr-namespace:ABBI_XPlat_3.Pages;assembly=ABBI_XPlat_3"
x:Class="ABBI_XPlat_3.Pages.ServiceListPage"
SelectedItem="{Binding CurrentTab, Mode=TwoWay}"
Title="Control ABBIs">
<pages:BaseTabbedPage.ToolbarItems>
<ToolbarItem x:Name="DisconnectButton" Name="Disconnect" />
</pages:BaseTabbedPage.ToolbarItems>
<pages:BaseTabbedPage.Children>
<pages:ProfilesPage Title="Profiles" />
<pages:VolumePage Title="Volume" />
<pages:SensitivityPage Title="Sensitivity" />
<pages:RemoteCtrlPage Title="Remote Control" />
</pages:BaseTabbedPage.Children>
</pages:BaseTabbedPage>
All the children pages use the same viewmodel. Which I navigate to using mvvmcross:
ShowViewModel<ServiceListViewModel>(new MvxBundle(bundle));
I have tried to Bind the CurrentTab property in the viewmodel, but the setter never gets called when I change tabs.
How can I detect which Tab is active then?
Related
I have a custom page template defined as follows :
Page1 :
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="MyApp.Resources.Controls.Page1"
Title="Page1">
<ContentPage.ControlTemplate>
<ControlTemplate>
<Grid RowDefinitions="auto,*">
<Label Text="Label 1" Grid.Row="0">
<!-- Content of page 1 -->
<ContentPresenter Grid.Row="1" />
</Grid>
</ControlTemplate>
</ContentPage.ControlTemplate>
</ContentPage>
All the pages inheriting from Page1, have "Label 1". So this is working fine.
Now I need to create a new custom page inherting from Page1. Basically adding new elements to the template and keep what is already in Page1.
Page2 :
<?xml version="1.0" encoding="utf-8" ?>
<Controls:Page1 xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="MyApp.Resources.Controls.Page2"
xmlns:Controls="clr-namespace:MyApp.Resources.Controls"
Title="Page2">
<Controls:Page1.ControlTemplate>
<ControlTemplate>
<Grid RowDefinitions="auto,*" >
<Label Text="Label 2" Grid.Row="0">
<!-- Content of page 2 -->
<ContentPresenter Grid.Row="1"/>
</Grid>
</ControlTemplate>
</Controls:Page1.ControlTemplate>
</Controls:Page1>
Now the pages inheriting from Page2 don't have "Label 1". They have only "Label 2". While I'm expecting these pages to have both "Label 1" and "Label 2"
Does anyone know how to solve that please ?
Thanks.
Short version of what you can do:
Make custom control class (lets say in namespace Controls), inheriting ContentView
public class MyControl : ContentView
In ResourceDictionary, add control template, and inside it, add your VisualElements.
< ControlTemplate x:Key="MyControlTemplate" >
...
< /ControlTemplate >
In your View, add your control:
< controls:MyControl ControlTemplate="{StaticResource MyControlTemplate}" />
Where controls is:
xmlns:controls="clr-namespace:MyNamespace.Controls"
And now your user interface can be reused in every page you want.
(And bind commands/properties to it, use different templates, etc...)
Best part is that you make changes at one place, and it is changed across your whole project.
The "new" and recommended way to display a modal page with the Xamarin.Forms Shell uri-based navigation is to set this tag in the XAML file (source): Shell.PresentationMode="ModalAnimated"
and to navigate to it by using a standard route and invoking it with the function Shell.Current.GoToAsync("routeToMyPage").
However, this displays the modal page without a toolbar. Without Shell navigation, I would have wrapped this page in a NavigationPage, but since the pages are initialized through reflection (at least that's what it looks like - don't quote me on this), I don't know how to do that.
Adding a ToolbarItem in the page's XAML code doesn't solve this, neither does the Shell.NavBarIsVisible="True" property, and adding a Button in the Shell.TitleView tag doesn't display a toolbar either.
Is there a way to display the default navigation toolbar without rendering a custom one myself?
Here is the XAML code I used to try to have the Toolbar displayed:
<ContentPage
xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
Shell.PresentationMode="ModalAnimated"
Shell.NavBarIsVisible="True"
x:Class="StackOverflow.Views.MyModalPage">
<ContentPage.ToolbarItems >
<ToolbarItem Text="Hi"/>
</ContentPage.ToolbarItems>
<Shell.TitleView>
<Button Text="Toolbar Button"/>
</Shell.TitleView>
<ContentPage.Content>
</ContentPage.Content>
</ContentPage>
Edit: I have created a small sample project to showcase my issue: https://github.com/Kuurse/StackOverflowExample
You can first create the NavigationPage root page in the app class:
public partial class App : Application
{
public App()
{
InitializeComponent();
MainPage = new NavigationPage(new MainPage());
}
}
Then set like this in your mainpage.xaml:
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="StackOverflow.Views.MyModalPage"
NavigationPage.HasNavigationBar="True">
<ContentPage.ToolbarItems>
<ToolbarItem Text="Hi"/>
</ContentPage.ToolbarItems>
</ContentPage>
By the way, do you want to display only the default navigation toolbar?
I have a ContentPage which is assigned to the Xamarin.Forms.Shell class as a ShellContent and require the back button to be displayed in the navigation bar of the ContentPage.
The XAML source of the ContentPage in concern is as follows:
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="UI_test.TestPage">
<Shell.NavBarIsVisible>True</Shell.NavBarIsVisible>
<Shell.BackButtonBehavior>
<BackButtonBehavior IsEnabled="True" />
</Shell.BackButtonBehavior>
<Shell.FlyoutBehavior>Disabled</Shell.FlyoutBehavior>
<ContentPage.Content>
<StackLayout>
<Label Text="Welcome to Xamarin.Forms!"
VerticalOptions="CenterAndExpand"
HorizontalOptions="CenterAndExpand" />
</StackLayout>
</ContentPage.Content>
</ContentPage>
I found that that assigning a custom value to the attributes TextOverride and IconOverride of the <BackButtonBehavior> tag will display the back button, but I am looking for a way to display the platform's default back button (rather than a custom one) as the above ContentPage does not display as back button in its navigation bar as seen in the screenshot below.
Thanks in advance.
Your project seems to contain one page only, It won't appear if no navigation has been made, and it makes sense. If you do a Shell.GotoAsync(..) or Shell.Navigation.PushAsync(..) to navigate to another page it will then appears (the default native back button) allowing to go back to the previous page in the navigation stack.
Now I got started with Prism Framework for xamarine, but I'm having a little problem achieving connections across views.
I have this folder "Views" and inside it I have another folder called PartialViews. Now inside PartialViews I have a contentPage called "Header.xaml".
Now I would like to atach this file to the Index.xaml view, which is located in the Views folder. I would like to atach the "Header.xaml" to other views also, like for example I would like to atach it to the "Orders.xaml" view.
My Header.xaml file is as follows :
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:prism="http://prismlibrary.com"
xmlns:local="clr-namespace:PROJECTX.Views"
prism:ViewModelLocator.AutowireViewModel="True"
x:Class="PROJECTX.Views.Header">
<StackLayout>
<Label Text="Trying partial views" />
</StackLayout>
</ContentPage>
While my Index.xaml is as follows:
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:combobox="clr-namespace:Syncfusion.XForms.ComboBox;assembly=Syncfusion.SfComboBox.XForms"
xmlns:ListCollection="clr-namespace:System.Collections.Generic;assembly=mscorlib"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:prism="http://prismlibrary.com"
xmlns:local="clr-namespace:PROJECTX.Views"
prism:ViewModelLocator.AutowireViewModel="True"
x:Class="PROJECTX.Views.Index"
x:Name="selfi">
<ScrollView>
<local:Header mvvm:ViewModelLocator.AutowirePartialView="{x:Reference selfi}" />
<combobox:SfComboBox x:Name="comboBox">
<combobox:SfComboBox.ComboBoxSource>
<ListCollection:List x:TypeArguments="x:String">
<x:String>Rendit sipas: Me te kerkuara</x:String>
<x:String>Rendit sipas: Te fundit</x:String>
<x:String>Rendit sipas: Alfabetit</x:String>
</ListCollection:List>
</combobox:SfComboBox.ComboBoxSource>
</combobox:SfComboBox>
</ScrollView>
</ContentPage>
I also registred on my App.xaml.cs the routing of the PartialViews folder with the view model like this:
protected override void RegisterTypes(IContainerRegistry containerRegistry)
{
containerRegistry.RegisterForNavigation<NavigationPage>();
containerRegistry.RegisterForNavigation<MainPage, MainPageViewModel>();
containerRegistry.RegisterForNavigation<Index, IndexViewModel>();
//containerRegistry.RegisterForNavigation<Header, HeaderViewModel>();
ViewModelLocationProvider.Register<Header, HeaderViewModel>();
}
Now I get a few errors...
1. The property 'Content' is set more than once.
2. The attachable property 'AutowirePartialView' was not found in type 'ViewModelLocator'.
3. Property 'Content' does not support values of type 'Header'.
Now I know this might be a rookie question, but I just can't seem to get it to work this partial views thing.
Is my understanding of partial views in xamarin correct? I'm supposed to call the partial view from the view.. correct?
Any help I would really really appreciate.
So you have to understand that in Xamarin forms, you can only have one ContentPage object for a page, hence you are getting the error “Content is set more than once”. You can however have multiple Layouts inside a single page
Here’s a quick snippet explaining pages versus layouts
Since you’re looking to use the Prism "PartialViews", a common way of referencing them is a "Template". So you’d have a HeaderTemplate file as you have shared. But instead of a ContentPage object, you would use a ContentView object (which is of type Layout) and you would define the content of the header inside that. (Official Docs)
And then you can add it to any page using this line inside your XAML as you would add a regular layout:
<templates: HeaderTemplate/>
I am working on a Xamarin Forms project that uses an MVVM pattern and Prism.
My issue is, I need to be able to hide a tab on a tab page based off of a bool. There is a bindable property in the XAML called "IsVisible", which I assumed would hide the tab from the user, but instead the tab still shows but displays a blank page when selected.
Currently my XAML looks like this
<?xml version="1.0" encoding="utf-8"?>
<TabbedPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms"
xmlns:local="clr-namespace:com.XXXXXXX"
prism:ViewModelLocator.AutowireViewModel="True"
BackgroundColor="White"
x:Class="com.XXXXXXXXXX.EditChargePage"
Title="{Binding Title}">
<local:EditChargeDetailsPage Title="Details" />
<local:EditChargeTrackingPage Title="Tracking" IsVisible="{Binding TabContext.HasTracking}" IsEnabled="{Binding TabContext.HasTracking}"/>
<local:EditChargeNotesPage Title="Notes" />
</TabbedPage>
Originally to solve the problem I just used "IsVisible", when that didn't work as expected I added "IsEnabled" which didn't seem to do anything.
Is there a way to hide the Tab from the UI using a boolean value in Xamarin (or Prism for Xamarin) without breaking MVVM?
You might want to check out the Prism Samples. The TabbedNavigation sample demonstrates how to initialize your tabbed children with INavigatingAware or the IEventAggregator, as well as dynamically adding the tabs at run time. If you need even finer control, such as a value in a ViewModel of one of your Child Pages that determines whether some other page should be shown, then you could use this to publish an event with the IEventAggregator and subscribe to that event in your TabbedPage to handle adding or removing the page.
Unfortunately IsVisible and IsEnabled do not actually work within a TabbedPage the way you were hoping. So the only way you can accomplish this is to actually manipulate the Children of the TabbedPage directly pushing or popping them from the collection.